Defrost water drain seal



Aug. 28, 1962 K. A. ROBBIE DEFROST WATER DRAIN SEAL Filed Sept. 26, 1960FIG.\

7 J T; a a Z a y N m 2 MA m 'Ar"' 7 x w w m 4 mm m HIS ATTORNEY UnitedStates Patent Office 3,050,957 Patented Aug. 28, 1952 3,050,957 DEFRQSTWATER DRAIN SEAL Kenneth A. Robbie, Louisviiie, Ky., assignor to GeneralElectric Company, a corporation of New York Filed Sept. 26, N60, Ser.No. 58,418 3 Claims. (Cl. 62-285) The present invention relatesgenerally to refrigerator cabinets and is more particularly concernedwith an improved defrost water drain seal for such cabinets.

A refrigerator cabinet including a low temperature or freezercompartment and an evaporator for serving that compartment requires somemeans for collecting the defrost water flowing from the evaporatorduring the periodic defrosting thereof and for disposing of this wateroutside of the cabinet. To this end there is usually provided a troughor equivalent means associated with the evaporator for collecting thedefrost water during the defrost operation and a drain for transferringthe collected water to a point outside the freezer compartment. As sucha drain provides a direct communication between the interior of thefreezer compartment and the exterior of the cabinet, it is desirable toprovide means for sealing the drain during normal operation of therefrigerator to prevent the flow of warm outside air into the freezercompartment or the flow of cold air from the compartment. The provisionof some sealing means is particularly important in refrigerators inwhich a fan is employed to circulate air from the freezer compartmentover the evaporator since the pressure differentials caused by the fancan force a relatively substantial amount of cold air out of the drainsystem resulting in a loss of refrigeration capacity or it can draw warmmoist airinto the freezer compartment with a resultant localized icingof the drain trough and adjacent portions of the evaporator. Anadditional requirement in refrigerators in which automatic means areprovided for periodically defrosting the freezer evaporator is that theseal must be readily opened during the defrost operation in order topermit the free drainage of defrost water through the drain.

It is a primary object of the present invention to provide in arefrigerator cabinet an improved drain seal which will effectively sealthe defrost water drain during normal operation of the freezerevaporator and which is so constructed and arranged that during defrostoperation of the refrigerating system the seal will be easily broken topermit the drainage of defrost water.

A more specific object of the invention is to provide an improved lowmass drain seal adapted, by the collection of frost thereon duringnormal operation of the evaporator, to seal the drain and prevent theflow of air therethrough and to be readily heated during the defrostingof the evaporator to open the drain for the disposal of defrost watertherethrough.

A further object of the invention is to provide a drain seal which canbe easily removed for cleaning and can also be employed for the purposeof periodically cleaning the drain system.

Further objects and advantages of the present invention will becomeapparent as the following description proceeds and the features ofnovelty which characterize the invention will be pointed out withparticularity in the and having an upper portion disposed within thefreezer compartment where it is subjected to the sub-freezingtemperatures of that compartment. For the purpose of preventing the flowof air through the drain during normal operation of the refrigeratingsystem there is provided a drain seal in the form of a brush having itsbristle or head portion positioned within the upper drain portion insuch a manner that the bristles extend across the drain and into contactwith the side walls thereof. During normal operation of the system, warmmoisture-laden air migrating from the outside of the cabinet through thedrain results in the formation of a frost layer on the brush bristleswhich bridges the spaces between the bristles and effects an air tightsealing of the drain. In order to melt this frost seal during defrostingof the evaporator, means are also provided for warming the upper portionof the drain in the vicinity of the brush head during the defrostoperation.

For a better understanding of the invention reference may be had to theaccompanying drawing in which:

FIG. 1 is a side view partially in section, of a refrigerator cabinetembodying the present invention;

FIG. 2 is an enlarged vertical sectional view of the improved drain sealof the present invention;

FIG. 3 is a horizontal sectional view of the drain system taken alongline 3-3 of FIG. 2; and

FIG. 4 is an enlarged end view of the freezer evaporator unit.

Referring now to the drawing there is shown in FIG. 1 a householdrefrigerator of the two temperature type comprising an outer shell 1,and inner shells or liners 2 and 3 spaced from the outershell 1 and fromone another, the spaces being filled with suitable heat insulation 4.The upper shell 2 defines a fresh food storage compartment 5 which ismaintained at fresh food storage temperatures by means of an evaporator6 while the lower liner 3 defines a freezer compartment 7 maintained atsub-freezing temperatures by an evaporator unit 8. The refrigerator alsoincludes a machinery compartment 9 below the freezer compartment, themachinery compartment containing a compressor 10 and a condenser 11 forsupplying condensed refrigerant to the evaporators. The freezerevaporator unit 8 includes evaporator tubing 14 disposed within alouvered metal housing 15. Air from the freezer compartment iscirculated through the housing and over the evaporator 14 by means of afan 16 centrally positioned in the front wall of the housing.

During normal operation of the refrigerator, the freezer evaporatortubing 14 which operates continuously at subfreezing temperaturesbecomes covered with an insulating layer of frost and ice condensed fromthe air circulated within the freezer compartment. In order to maintainthis evaporator at the desired operating efficiency, means are providedfor warming the evaporator periodically to defrosting temperatures inorder that the frost and ice layer will melt from the evaporator tubing.This heating means may be an electrical heater or any of the variousarrangements for conducting hot compressed refrigerant from thecompressor 10 through or in heating relationship with the evaporatortubing. In the illustrated modification of the invention there isemployed a defrost system of the type described and claimed in Patent2,928,256 issued on March 15, 1960, to Clyde 1. Nonornaque and assignedto the same assignee as the present invention. In accordance with theteachings of the Nonomaque patent, hot compressed refrigerant from thecompressor is periodically directed through an auxiliary defrost line 17which is in heat exchange with the evaporator tubing 14.

During defrost operation and as the evaporator tubing 14- is heated tofrost melting temperatures, any frost collected on the evaporator or onthe adjacent surfaces of the housing 15 is melted. The defrost waterflowing from these surfaces is collected in a V-shaped bottom wall 18forming the bottom of the housing 15 from which it is discharged into adrain 19 extending through the bottom insulated wall of the cabinet fordirecting the defrost water into the machinery compartment 9 where areceptacle (not shown) may be provided for receiving the defrost waterand evaporating it by means of the heat from the compressor andcondenser.

For the purpose of sealing the drain 19 to prevent the flow of airtherethrough during normal or refrigerating operation of the evaporator,there is provided in accordance with the present invention a drain sealin the form of a brush 22 having, as is more particularly shown in FIGS.2 and 3 a head or bristle portion 23 of approximately the same size andshape as the upper portion of the drain 19. This head portion 23 isinserted into the drain in such a manner that the bristles 24, of metal,nylon or any other bristle material, extend transversely to the draininto contact with the Walls thereof. In the illustrated embodiment ofthe invention the upper portion of the drain 19 is in the form of a tubeso that a brush having a cylindrical head portion, such as a bottlebrush of a diameter somewhat larger than the internal diameter of thedrain provides a particularly useful drain seal. To facilitate removalof the brush 22 from the drain the handle portion 26 is preferablysufiiciently long so that it extends above the drain where it can beeasily grasped by the user for removal of the brush from the drain forcleaning the brush. Also by this arrangement the brush can be moved upand down through the upper portion of the drain during the defrostperiod in order to dislodge any particles of foodstuff or other materialtherefrom.

Warm air passing upwardly from the machinery compartment through thedrain during normal or refrigerating operation of the refrigeratingsystem will carry with it a substantial amount of moisture. Thismoisture, upon contacting the bristles 24 which are cooled by contactwith the walls of the upper portion of the drain disposed within thefreezer comparment 7, condenses on the bristles in the form of lighthairy layers of frost and after a short time these frost layers willbuild up to a point Where they bridge the spaces between the bristles 24to form a continuous plug of frost 28 that completely seals the drain.Once the drain is thus sealed, air is prevented from thereafter passingin either direction through the drain tube.

In order to remove this sealing body of frost during each defrost periodso that defrost water can freely drain, means are provided for Warmingthe upper portion of the drain tube 19 at the same time that theevaporator is being warmed. This Warming means may be part of the samemeans employed to warm the evaporator tubing 14 to defrost temperaturesor it may be a separate heating means. In the illustrated embodiment ofthe invention, the drain 1% is warmed by a portion 29 of the defrostline 1'7 employed to conduct hot compressed refrigerant from thecompressor into heat exchange relationship with the refrigerant tubing14. Preferably, at least th upper portion of the drain 19 is composed ofmetal 1 for good heat conduction between the section 29 of the defrosttubing and the drain as well as between the drain and the bristles 24.Since the bristles 24, provide a relatively low mass seal, that is onehaving a low heat storage capacity, the sealing frost layers accumulatedon these fibers will melt at an early stage during the defrost cyclebefore any substantial amount of water has drained from the higher massevaporator. Melting of the frost plug 29 permits the defrost water toflow through the spaces between the bristles. Due .to their relativelysmall diameters, Water will not tend to adhere to or collect in anysubstantial amounts on these bristles. As a result, no substantialquantities of ice are formed thereon during the subsequent refrigeratingcycle, which ice would require a longer period of time to melt and openthe drain than does the light Weight or low density frost accumulationof the type resulting from the condensation of moisture from the airpassing through the drain following a defrost cycle and during the earlystages of the subsequent refrigerating cycle.

While there has been shown and described a particular embodiment of thepresent invention, it will be understood that the invention is notlimited to the particular form and it is therefore intended by theappended claims to cover all modifications coming within the spirit andscope of the invention.

What I claim as new and desire to secure by Letters Patent of the UnitedStates is:

1. A refrigerator cabinet comprising an evaporator normally operating ata sub-freezing temperature, means for collecting defrost water from saidevaporator during defrosting thereof and disposing of the defrost wateroutside said cabinet including a drain extending through a wall of saidcabinet and having an upper portion normally cooled by said evaporatorto a temperature below freezing and combination means for cleaning saiddrain and for effecting a deposit of frost in said drain for closingsaid drain during normal operation of said evaporator comprising abristle brush removably positioned in said upper drain portion with theends of the bristles thereof contacting the inner walls of said drain.

2. A refrigerator cabinet comprising an evaporator normally operating ata sub-freezing temperature, means for periodically'warming saidevaporator to defrosting temperatures, means for collecting defrostWater from said evaporator and disposing of the defrost water outsidesaid cabinet including a tubular drain extending through a wall of saidcabinet and having portion normally cooled by said evaporator to atemperature below freezing and a cylindrical brush removably positionedin said upper drain portion with the bristles thereof extending acrosssaid drain with the ends thereof contacting the side wall of the drainwhereby frost collecting on said bristles during normal operation ofsaid evaporator seals said drain.

3. A refrigerator cabinet comprising an evaporator normally operating ata sub-freezing temperature, means for periodically warming saidevaporator to defrosting temperatures, means for collecting defrostwater from said evaporator and disposing of the defrost water outsidesaid cabinet including a drain extending through a wall of said cabinetand having an upper portion normally cooled to a temperature belowfreezing, and a bristle brush removably positioned in said upper drainportion with the ends of the bristles contacting the side wall of thedrain whereby frost collecting on said bristles during normal operationof said evaporator seals said drain and means for warming said upperportion of said drain during defrosting of said evaporator to melt thefrost accumulated on said bristles.

References Cited in the file of this patent UNITED STATES PATENTS2,187,470 Collins Jan. 16, 1940 2,303,138 Philipp Nov. 24, 19422,485,630 Munters Oct. 25, 1949 2,511,419 Smith Jan. 13, 1950 2,723,534Wilbushewich Nov. 15, 1955 2,767,558 Wallenbrock et al. Oct. 23, 19562,775,873 Jones Jan. 1, 1957

